Method and apparatus for burning fluent fuel



y 1952 D. M. MARSHALL 3,032,097

METHOD AND APPARATUS FOR BURNING FLUENT FUEL Filed July 7, 1958 2Sheets-Sheet 1 FIG.7

INVENTOR.

David M. Marshall ATTORNEY D. M. MARSHALL 3,032,097

METHOD AND APPARATUS FOR BURNING FLUENT FUEL May 1962 Filed July 7, 1958INVENTOR.

David M. Marshall ATTORNEY 2 Sheets-Sheet 2 United States Patent OfificePatented 3,032,097 IVHETHGD AND APPARATUS FOR BURNING FLUENT FUEL DavidM. Marshall, Packanack Lake, N.J.. assignor to The Bahcock 8: WilcoxCompany, New York, N.Y., a

corporation of New Jersey Filed July 7, 1958, Ser. No. 746,689 12Claims. (6i. 158-11) This invention relates to a method and apparatusfor burning a fluent fuel, and more specifically to an improved methodand apparatus for burning a gaseous fuel, the instant inventionconstituting an improvement over that disclosed in US. Patent No.2,826,249.

In firing furnaces or combustion chambers of a vapor or steam generatorand the like, it is generally customary to utilize burner means capableof burning either oil, gas and/or coal, separately or in combinationdepending on the amount and availability of a particular fuel.Combination oil and multiple spud gas burners of the kind disclosed inthe aforementioned patent have been found to be generally satisfactoryfor firing steam generators, for example, where oil and gas are theprincipal fuels to be burned. However, in the operation of the multiplespud gas burner having all of the gas discharge orifices located in thetip end of the spuds, actual experience has shown that at gas pressuresof approximately 1 lb. per sq. in. occurring at the lower boiler loads,flame instability and poor combustion are noted with the flame beingcompletely extinguished when the gas pressure drops to lb. per sq. in.When such flame-out occurs likeli hood of an explosion in the furnace isquite possible.

Therefore an object of this invention is to provide a novel method andmeans for burning a fuel so as to attain reliable flame stability andgood combustion at very low fuel pressures, e.g. at gas pressure rangingfrom 1 lb. per sq. in. to less than that of 4 inches of water gaspressure which is desirable for very low load operation of a steamgenerator.

Another object is to provide an improved method of burning fuel andmeans for practising the same wherein the requisite stability and goodcombustion characteristics at very low fuel pressures are attained overan extended range of burner capacities.

The method by which the above objects are attained comprises essentiallythe steps of imparting a whirling motion to a supply of combustion airto form a whirling band of air and introducing a fluent fuel into theband of whirling air to be mixed therewith. Accordingly, the fuel isdivided into a plurality of fuel streams for in troduction into thewhirling band of air, a portion of the fuel streams being introducedthereinto with directional components generally counter to and radiallyinwardly toward the center or vortex of the rotating or whirling band,and another portion of the fuel streams being introduced thereinto in asubstantially diametrically opposed direction with directionalcomponents which are generally in the direction of the whirling band ofair and radially outwardly toward the outer periphery thereof.

While the gas burning apparatus for practicing the foregoing method maybe susceptible of a number of variations of a preferred form to beherein described, the instant gas burning apparatus and the variationsthereof for practising this invention comprise essentially an airregister arranged in communication with a burner port which extendsthrough a wall portion of a combustion chamber, means for imparting awhirling movement to the combustion air to form a rotating band of air,and a fluent fuel or gas burner for ejecting the fuel into the band ofair in a definite manner with respect thereto to be mixed therewith.More specifically the gas burner includes an endless or annular gasmanifold which is re moved from the heat of the furnace and is arrangedto be disposed in a plane parallel to the plane of a burner throat portin a furnacewall, the manifold being connected to a source of gas supplyunder pressure. Spaced about the gas manifold and connected theretopreferably by readily releasable coupling means are a plurality ofindividually removable elongated gas spuds which are substantially equalin length and which extend through the air register and toward theburner throat, the tip ends of the gas spuds being arranged so as tohave their free ends terminate in a plane substantially parallel to theentrance opening of the burner throat. Where the gas burner, hereindescribed, is utilized in conjunction with an oil burner as disclosed inU.S. Patent 2,826,249, the free ends of the gas spuds are likewisedisposed in a circle concentric about an impeller utilized inconjunction therewith.

According to this invention each of the gas spuds are disposed withinthe whirling band of air so as to have an opposed windward and leewardwall portion with respect to the whirling air, each spud having aplurality of gas discharge orifices longitudinally spaced in thewindward wall portion and arranged to direct streams of gas into thewhirling air band with directional components that are generally counterto and toward the inner periphery of the whirling air band.Substantially diametrically opposed orifices located in the leeward wallportion are an ranged to discharge other streams of fuel withdirectional components that are generally in the direction of and towardthe outer periphery of the air flow. If desired the face portion of thespud exposed to furnace radiation may be provided with a fuel dischargeorifice whereby the relatively cool gas flowing therethrough serves tocool thetipend. Y

A feature of the invention resides in the provision whereby the instantgas burner may be utilized in conjunction with a liquid fuel burner andmay be fired separately or in combination therewith.

Another feature resides in the provision of an improved gas spud havingan extended range of capacities.

Still another feature resides in the provision wherein the low pressurelimit at which flame-out occurs is materially lowered.

And still another feature resides in the provision that the operatingload range of a steam generator utilizing the instant burner arrangementis appreciatively increased.

And still another feature of this invention resides in the provisionthat the improved gas burner is relatively simple in construction,economical to fabricate, easily maintained and positive in operation.

Other features and advantages will be readily apparent when consideredin view of the drawings and description in which FIG. 1 is a sectionalside view of the improved gas burner of the instant inventionillustrated in conjunction with a liquid fuel burner;

FIG. 2 is a furnace end view of the improved burner of this inventionillustrating the manner in which the streams of fuel gas are introducedwith respect to the whirling band of air.

FIG. 3 is an enlarged detail view of the fuel discharge end portion ofan improved gas spud in accordance with this invention.

FIG. 4 is a furnace end view illustrating the face portions of the gasspud illustrated in FIG. 5.

FIG. 5 is a section taken along line 55 of FIG. 3.

FIG. 6 is an enlarged detail view of a modified gas spud fuel dischargeend portion.

FIG. 7 is a front view of the spud illustrated in FIG. 6.

While the burner of the instant invention may be utilized as a gasburner only, it will be noted that the novel gas burner arrangementherein described is readily adapted for use in a multiple fuel burnerarrangement whereby either a liquid fuel atomizing means and/ or apulverized coal .burning means may be utilized in conjunction therewithfor burning an alternate fuel, either separately or in combinationtherewith. However, for the purpose of description, the improved gasburner of the instant invention is herein illustrated in an arrangementin combination with a liquid fuel burning means.

Referring to the drawings, the burner combination is illustrated withthe instant gas burning means 11 in combination with a liquid fuelatomizing means 12 which may be, for example, of the type shown in U.S.Patent 2,260,062. Accordingly, the liquid fuel atomizing means 12 ismounted centrally of a circular type burner 10 whichis in alignment withburner throat 13 extending into port 14 formed in a wall portion 15 of afurnace of a steam generating unit or the like. The burner throat 13 isformed of a suitable refractory material and includes a cylindricalrelatively short entrance section 13a which is continuou with adiverging conduit section 1% leading into the interior of the furnace.Spaced from the furnace wall 15 and extending substantially parallelthereto is an outer casing 16 in which the space formed therebetweenconstitutes an air plenum 17 for the how of combustion air from a forceddraft fan (not shown) to the burner port.

An air entrance means in the form of a truncated cone 18 is supportedimmediately adjacent to the exterior side of the port 14 to direct airinto the port. In the illustrated arrangement, the directing cone 18converges toward the entrance of the port, the cone being supported to astructural frame work extending between the furnace wall 15 and thecasing 16. The combustion air is directed to the come 18 from an airregister 1 having an outer wall 20 and an inner wall 21, inner wall 21being connected to the entrance cone 18. It will be noted that betweenthe walls 20 and 21, the air register is provided with adjustable airdoors 22 suitably controlled by operating means 23. The adjustment ofthe doors 22 impart a whirling or swirling movement to the air which issupplemented by a plurality of vanes 24 in cone 18 so that the airdischarging from the register tends to'form a whirling band of airhugging the peripheral portion of the throat.

An annular cover plate 25 closes an access opening 26 in the casing 16and a cylindrical housing or casing 27 extends inwardly from the innerperiphery of the access cover plate 25 through the air plenum 17 to theouter wall 20 of the air register 19, the casing or housing 2'7embracing the burner means 11 and 12 which extend therethrough. Theouter ends of the two fuel dispersing means 11 and 12 extend through thesmall circular cover 28 closing the central opening in the annular coverplate 25, the circular cover 28 forming an outer closure for the casingor housing 27.

The circular cover 28 supports a central sleeve member 29 through whichthere extends a distance piece 39 forming part 'of the fuel oil atomizer12. If desired, the distance piece 30 may be rendered axially adjustablealong the central axis of the burner 10. At the outer end of thedistance piece there is connected thereto a liquid fuel supply assembly31 which connects the fuel pipe or oil burner barrel 32 disposedcentrally of the distance piece 30 with a source of fuel and oil (notshown). On the innerend of the barrel 32, there is provided a fuelatomizing head 33 which is spaced a short distance from the burner port,the atomizing head 33: being preferably of the type producing a conicalspray of atomized oil having the axis of the conical spray co-axial withthe entrance cone 18 and the burner port 14.

Attached to the inner end of the distance piece 30 and externallysurrounding the atomizer head 33 is an air deflector or impeller meansin the shape of a truncated cone 34 having the base 34a thereofextending outwardly toward the furnace chamber, the impeller-cone beingconcentrically disposed about the longitudinal axis of the burner meansit). The conical surface of the impeller means is provided with a seriesof equally spaced air openings 35 and corresponding air deflector platesor vanes 36 associated therewith for imparting a whirling motion to theair directed through the impeller to the central portion of the burnerport. If desired, an observation port (not shown) may be provided in thecircular cover 23. Also an igniting means (not shown) is provided.Intermediate the ends of the distance piece 30 and more closely adjacentthe forward end of the oil burner 12, there is provided a support memberor spider 38 for supporting the distance piece in position within thecasing 27.

The improved gas burner arrangement 11 of the instant invention includesan endless or annular gas manifold 39 disposed in a plane substantiallyparallel to the burner port 14 and spaced therefrom, the manifold 3?being disposed immediately adjacent the cover plate 28 on the outer sidethereof. Means (not shown) are suitably arranged to connect the manifoldto a suitable source of gas supply under pressure. Spacially disposedand preferably equidistantly spaced about a peripheral portion of thegas manifold, there are provided a plurality of nipples 4% incommunication with the interior of the manifold 39.

r Releasably connected to the other end of each nipple 4% is anelongated gas conduit or spud 42. As shown the plurality of elongatedgas spuds 42 are concentrically disposed about the longitudinal axis ofthe burner, the spuds 42 extending through spaced openings 43 in thecircular cover 28 and inwardly through the casing 27 toward the burnerport 14.

In accordance with this invention the gas spuds may have a discharge endportion conforming to a number-of different shapes, two forms of whichare herein illustrated. Referring to FIGS. 3 to 5 the discharge endportion of the gas spuds includes a tip end 43 having a pairofconverging side faces 44 disposed in planes extending at oppositeoblique angles to an axial plane of the spud and intersect therein, theside faces 44 terminating just short of the line of intersection. Theside faces 44 thus formed are joined by a relatively narrow central faceportion '45. The opposite ends of the central face portion 45 terminatein end faces 46 which are located in oblique planes disposed at rightangles to the oblique planes of the side faces 44. Because the tip 43 isexposed to the heat of furnace radiation, it is preferably made of ahigh heatresistant alloy casting and is joined by suitable means to analloy pipe which forms the barrel portion 4'7 of the spud. In additionthe faces 44, 45 and as may be provided with one or more orifices 48 sothat the relatively cool gases flovyiing therethrough assists inmaintaining the tip end 43 coo Important to the successful operation ofthe instant gas burner is the particular arrangement of the dischargeorifices 49 spaced longitudinally along the barrel portion 47 of thespuds 42 adjacent the tip end 43 as will now be described.

Referring to FIG. 5 it will be noted that the orifices 49 in a wallportion of the spud barrel have diametrically disposed counterpartorifices 49 in the opposite Wall portion thereof, the arrangement beingsuch that a major portion of the orifices 49 in one of the wall portionslie below the horizontal axial plane, as viewed in FIG. 5, while theorifices 49' diametrically opposed thereto in theopposite wall lie abovethe horizontal axial plane. For example, in a gas burner having acapacity of 63 MBK/hr. and having 8 spuds as illustrated, the dischargeend portions of the spud barrels are drilled so as to have four rows ofradially drilled orifices A, B, C, and D in one wall and diametricallydisposed rows A, B, C, and D of orifices 49 disposed in the oppositeWall; the orifices in one row being staggered relative to the orificesin the next adjacent row. It is to be further noted that the rows ineach of the opposed wall portions are angularly displaced from oneanother by approximately 11% so that row A is positioned atapproximately 22 /2" below the horizontal centerline as viewed in FIG. 3and row D being approximately 11% above the centerline. Thus the spacingof the diametrically disposed row of orifices A B C and D' with respectto the horizontal centerline, as viewed in FIG. 3, is opposite to thatof rows A, B, C and D. For example, orifices 4% in row A areapproximately 22 /2 above the centerline and row D being approximately11% below the centerline, rows C and C being on the centerline.

In accordance with this invention the spuds 42 with the drillings hereindescribed are disposed within the band of whirling air and are arrangedso that their discharge end portions are disposed adjacent the throat 13in the circle concentric with the periphery thereof. It will be furthernoted that the spuds are arranged so that the central face portion 45 ofeach spud is disposed radially about the axis of the burner as best seenin FIG. 2. With the spuds 42 so arranged it will be noted that the wallportion containing rows A, B, C and D is directed into the rotating airto form the windward side of the spud when the band of air is whirlingin a counterclockwise direction as indicated by the air flow arrows St)in FIG. 2. Thus the wall portions of each spud containing row A, B, Cand D is directed away from the flow of air and constitutes the leewardwall portion of the spuds.

With the spuds thus disposed Within the rotating air band, orifices 4-5on the windward wall portion tend to discharge a major portion of thegases issuing therefrom in a direction which is generally counter to therotation of the air flow and toward the axis or inner periphery of therotating band of air as indicated by arrow 51. The orifices 4 9' in theleeward wall portion of the spud 42 on the other hand tend to direct amajor portion of the gases in the general direction as that of therotating air and outwardly toward the outer periphery thereof asindicated by arrows 51A, in which the resultant directional component isgenerally opposite that which occurs on the windward wall portion. Withthis arrangement wherein the spud drillings or orifices 49, 49' in thebarrel portion 47 thereof direct the major portion of the gasesoutwardly therefrom in the directions described with respect to thedirection of the whirling band of air, experiments have indicated thatgood combustion characteristics are attained at gas pressure below 4inches of water. This is believed to be due to the particulardirectional components and velocities of the gases with respect to thatof the rotating air flow which results in more of the gas beinginfluenced by the whirling band of air in a manner to enhance mixing ofthe gas and air.

With the arrangement above described it has been further discovered thatflame stability is likewise enhanced throughout the operating range ofthe gas burner. This is believed to be due to the eddies or turbulencecreated by the air in flowing over the barrel portion 4-7 of the spuds42 to produce a condition that tends to promote flame stabilization.

The spud arrangement illustrated in FIGS. 6 and 7 is identical to thatof FIG. 3 with the exception that at the face portion 52 thereof is Hatand has at least one orifice 53 therein for cooling as hereinbeforedescribed. When utilized in a burner arrangement as described, theorifices 5'4 in the barrel portion 55 thereof are disposed with respectto the air flow in the same manner as herein de scribed.

In the gas burner arrangement described it will be noted that thecapacities or rating of the burner may be readily increased or decreasedas may be required by either increasing or decreasing the number ofspuds and/ or varying the number of orifices in the barrel portionthereof. Since the capacity of a spud burner is largely dependent on thenumber of orifices drilled therein, it will be noted that by spacing theholes along the length of the barrel substantially in the mannerdescribed a greater range of burner capacities may be attained overthose spud arrangements wherein orifices are restricted to the tip endonly and thus limited in number of orifices which could be disposedtherein due to the relatively small area thereof. Thus the capacity ofthe instant arrangement is not limited by the area of the tip ends.

While the structural details of the gas burner described may varydepending on desired burner size or capacity which may require more orless spuds and/or orifices drilled therein, the method of burning thegaseous fuel remains unchanged. Generally the improved method of burninga gaseous fuel which is practiced by an embodiment of the apparatusherein described comprises the steps of imparting a whirling movement toa supply of air to form a whirling mass or band of combustion air andintroducing a plurality of gas streams into the whirling air band at aplurality of substantially equally spaced points within the band ofwhirling air. Accordingly, at each point of gas introduction, the gas isinjected into the air stream in diametrically opposed directions. Withrespect to the direction of air flow, a portion of the gas introduced atthe given points is directed with a resultant component which is counterto the air flow and toward the inner periphery of the band of air andanother portion of the gas at the point being directed in an oppositedirection having a resultant component which is generally in thedirection of and toward the outer periphery of the moving band of air.

While the instant invention has been disclosed with reference to aparticular method and a particular embodiment for practising the same,it is to be appreciated that the invention is not to be taken as limitedto all of the details thereof as modifications and variations thereofmay be made without departing from the spirit or scope of the invention.

What is claimed is:

l. A burner comprising a throat adapted to extend through a furnacewall, an air register for receiving combustion air in communication withsaid burner throat, means for imparting a whirling movement to said airdischarging from said register to form a band of whirling air tending tohug the periphery of said throat, and burner means for discharging fuelinto said whirling band of air to be mixed therewith, said burner meansincluding a tubular spud having a tip end adjacent the throat anddisposed within the whirling band of air so as to have a wall portionthereof windward and an opposed wall portion thereof leeward withrespect to said whirling air, means supplying a fuel to said spud, saidspud having fuel discharge orifices disposed in said windward wallportion to direct the major portion of the stream of fuel dischargingtherefrom toward the inner periphery and counter to said whirling airband and fuel discharge orifices disposed in said leeward wall portionto direct a major portion of the stream of fuel discharged therefromtoward the outer periphery and in the general direction of said whirlingair band.

2. In combination with a furnace wall having a burner throat portextending therethrough, an air register for receiving combustion air incommunication with said burner throat port, means for imparting awhirling movement to said air discharging from said register to form aband of whirling air tending to hug the periphery of said throat port,and gas burner means discharging streams of gas into said whirling bandof air to be mixed therewith, said gas burner means including a tubulargas spud having a tip end adjacent the throat port and disposed withinthe whirling band of air so as to have a wall portion thereof windwardand an opposed wall portion thereof leeward with respect to saidwhirling air, means supplying a fuel gas to said spud, said spud havinga plurality of gas discharge orifices disposed in said windward wallportion to direct a major portion of the streams of gas dischargingtherefrom toward the inner periphery of said whirling air band and aplurality of orifices disposed in said leeward wall portion to direct amajor portion of the streams of gas discharging therefrom toward theouter periphery of said whirling air band, said orifices being spacedlongitudinally along a length of said spud adjacent the tip end thereof.

3. In combination with a furnace wall having a burner throat portextending therethrough, an air register for receiving combustion air incommunication with said burner throat port, means for imparting awhirling movement to said air discharging from said register to form aband of whirling air tending to hug the periphery of said throat port,and gas burner means discharging streams of gas into said whirling bandof air to be mixed therewith, said gas burner means including aplurality of elongated tubular gas spuds and each having its tip endadjacent the throat port, said gas spuds being disposed within thewhirling band of air so as to have a wall portion thereof windward andan opposed wall portion thereof leeward with respect to said whirlingair flowing thereover, means supplying a fuel gas to said spuds, each ofsaid spuds having a plurality of gas discharge orifices disposed in saidwindward wall portion to direct a major portion of the streams of gasdischarging from the windward orifices toward the inner periphery ofsaid whirling air band and a plurality of gas discharge orificesdisposed in said leeward wall portion to direct a major portion of thestreams of gas discharging from the leeward orifices toward the outerperiphery of said whirling air band, said orifices being adjacent thetip end and longitudinally spaced along a length of said spud.

4. In combination with a furnace wall having a burner throat portextending therethrough, an air register for receiving combustion air incommunication with said burner throat port, means for imparting awhirling movement to said air discharging from said register to form aband of whirling air tending to hug the periphery of said throat port,and gas burner means discharging streams of gas into said whirling bandsof air to be mixed therewith, said gas burner means including aplurality of elongated, tubular gas spuds having their tip ends adjacentand circumferentially spaced within the periphery of and about the axisof said throat port, said gas spuds being disposed within the whirlingband of air so as to have a wall portion thereof windward and an opposedwall portion thereof leeward with respect to said whirling air flowingthereover, means supplying a fuel gas to said spuds, each of said spudshaving a plurality of gas discharge orifices disposed in said windwardwall portion to direct a major portion of the streams of gas dischargingtherefrom toward the inner periphery of said whirling air band and aplurality of gas discharge orifices disposed in said leeward wall portonto direct a major portion of the streams of gas discharging therefromtoward the outer periphery of said whirling air band, said orificesbeing diametrically opposed and longitudinally spaced along a length ofsaid spud adjament the tip end thereof.

5. In combination with a furnace wall having a burner throat portextending therethrough, an air register for receiving combustion air incommunication with said burner throat port, means for imparting awhirling movement to said air discharging from said register to form aband of whirling air tending to hug the periphery of said throat port,and gas burner means discharging streams of gas into said whirling bandof air to be mixed therewith, said gas burner means including aplurality of elongated tubuiar gas spuds having their tip ends adjacentthe throat port, means supplying a fuel gas to said spuds, said tip endeach having a face portion disposed in a plane oblique to an axial planeof said spud, said face portions having a fuel discharge orificetherein, said gas spuds being disposed within the whirling band of airso as to have a wall portion thereof windward and an opposed wallportion thereof leeward with respect to said whirling air flowingthereover, each of said spuds having a row of gas discharge orificesdisposed in said windward til 0 0 wall portion to direct streams of gastoward the inner periphery of said whirling air band and a row of gasdischarge orifices disposed in said leeward wall portion to directstreams of gas toward the outer periphery of said whirling air band,said rows of orifices being diametrically opposed and extendinglongitudinally along a length of said spuds adjacent the tip endsthereof.

6. In combination with a furnace wall having a burner throat portextending therethrough, an air register for receiving combustion air incommunication with said burner throat port, means for imparting awhirling movement to said air discharging from said register to form aband of whirling air tending to hug the periphery of said throat port,and gas burner means discharging streams of gas into said whirling bandof air to be mixed therewith, said gas burner means including aplurality of elongated, tubular gas spuds having their tip ends adjacentthe throat port, means supplying a fuel gas to said spuds, each of saidtip ends having a pair of oblique face portions intersecting in an axialplane, a fuel discharge orifice in at least one of said face portions ofsaid tip ends, said gas spuds being disposed within the whirling band ofair so as to have a wall portion thereof windward and an opposed wallportion thereof leeward with respect to said whirling air flowingthereover, each of said spuds having a row of gas discharge orificesdisposed in said windward wall portion to direct streams of gas towardthe inner periphery of said whirling air band and a row of gas dischargeorifices disposed in said leeward wall portion to direct streams of gastoward the outer periphery of said whirling air band, said rows oforifices being diametrical- 1y opposed and extending longitudinallyalong a length of said spuds adjacent the tip ends thereof.

7. The invention as defined in claim 6 wherein said gas spuds arecircumferentially spaced within the periphery of and about the axis ofsaid throat port with the intersection of said oblique face portionsdirected radially about the axis of said port.

8. An improved combination oil and/or gas burner comprising a circularburner throat adapted to extend into a burner port in a furnace wall, anair register for receiving combustion air in communication with saidburner throat, means for imparting a whirling movement to said airdischarging from said register to form a band of whirling air tending tohug the periphery of said throat, an oil atomizing means extendingthrough said air register and toward said port, an impeller supported bysaid atomizing means adjacent said throat and concentrically disposedwith the periphery of said throat, and gas burner means dischargingstreams of gas into said whirling band of air to be mixed therewith,said gas burner means inbinding a plurality of elongated, tubular gasspuds circumferentially spaced about said atomizing means, meanssupplying a fuel gas to said spuds, said spuds having their tip endsdisposed adjacent the throat in a circle concentric with the peripheryof said throat, each of said tip ends having a face portion, a fueldischarge orifice in said face portions, said gas spuds being disposedwithin the whirling band of air so as to have a wall portion thereofwindward and an opposed wall portion thereof leeward with respect tosaid whirling air flowing thereover, each of said spuds having aplurality of gas discharge orifices disposed in said windward wallportion to direct a major portion of the streams of gas dischargingtherefrom toward the inner periphery of said whirling air band and aplurality of gas discharge orifices disposed in said leeward wallportion to direct a major portion of the streams of gas dischargingtherefrom toward the outer periphery of said whirling air band, saidorifices in said wall portions being diametrically opposed in rows thatextend longitudinally along a length of said spuds adjacent the tip endsthereof.

9. An improved combination oil and/or gas burner comprising a circularburner throat adapted to extend into a burner port in a furnace wall, anair register for receiving combustion air in communication with saidburner throat, means for imparting a whirling movement to said airdischarging from said register to form a band of whirling air tending tohug the periphery of said throat, an oil atomizing means extendingthrough said air register and toward said port, an impeller supported bysaid atomizing means adjacent said throat and concentrically disposedwith the periphery of said throat, and gas burner means dischargingstreams of gas into said whirling band of air to be mixed therewith,said gas burner means including an endless gas manifold, a plurality ofelongated, tubular gas spuds connected to and circumferentially spacedabout said manifold, said spuds extending through said air register andhaving their free tip ends disposed adjacent the throat in a circleconcentric with the periph ery of said throat, each of said tip endshaving a pair of face portions lying in oblique planes with respect toan axial plane of its respective spud and said oblique facesintersecting in said axial plane, a fuel discharge orifice in at leastone face portion of said tip ends, said tip ends being circumferentiallyspaced about the axis of said throat so that the respectiveintersections of the planes of said oblique face portions are radiallydisposed about said axis of said throat, said gas spuds being disposedwithin the whirling band of air so as to have a wall portion thereofwindward and an opposed portion thereof leeward with respect to saidwhirling air flowing thereover, each of said spuds having a row of gasdischarge orifices disposed in said windward wall portion to directstreams of gas toward the inner periphery of said whirling air band anda row of gas: discharge orifices disposed in said leeward wall portionto direct streams of gas toward the outer periphery of said whirling airband, said rows of orifices being diametrically opposed and extendinglongitudinally along a length of said spuds adjacent the tip endsthereof.

10. An improved method of burning a fluent fuel comprising the steps ofintroducing a supply of combustion air into an air register of a burner,imparting a whirling movement to said air to form a band of whirlingair, discharging a fluent fuel into said whirling band of air to bemixed therewith so that a portion of said fuel has a directional vectorgenerally counter to the direction of the whirling air and toward theinner periphery of said whirling band of air and another portion of saidfuel having a directional vector in the general direction of saidwhirling air and toward the outer periphery of said whirling band ofair.

ll. An improved method of burning a. fluent fuel comprising the steps ofintroducing a supply of combustion air into an air register of a burner,imparting a whirling movement to said air to form a band of whirling airas said air egresses from said register, introducing a fluent fuel intosaid whirling band of air to be mixed therewith, dividing said fuel intoa plurality of fuel streams, directing a portion of said fuel in adirection having a vector which is generally in a direction counter tothat of the whirling air and toward the inner periphery of said whirlingband of air and directing another portion of said fuel in a directionhaving a vector in the same general direction of said whirling air andtoward the outer periphery of said whirling band of air.

12. An improved gas spud comprising an elongated tubular fuel conduithaving a tip end and longitudinal ex tending opposed wall portionsdisposed on opposite sides of an axial plane extending longitudinally ofsaid conduit, said tip end having a face portion, said face portionhaving a fuel discharge opening therein, a plurality of fuel dischargeorifices spaced in rows angularly disposed about the axis of saidconduit, said rows extending longitudinally in each of said opposed wallportions of said conduit adjacent the tip end thereof, the rows oforifices in each of said wall portions being diametrically opposed andarranged so that a majority of the orifices in one of said opposed wallportions are disposed within a substantially 25 angle on one side of asecond axial plane extending longitudinally of said conduit and disposedperpendicular to said first mentioned axial plane and said second planeincluding one leg of said angle.

References Cited in the file of this patent UNITED STATES PATENTS1,093,499 Tobias Apr. 14, 1914 2,439,609 Mittendorf Apr. 13, 19482,826,249 Poole Mar. 11, 1958 FOREIGN PATENTS 310,580 Italy Aug. 25,1933

